Chapter 5: Analysing the Data |
Step 2: Checking assumptionsAll statistical tests make some assumptions about the form of the numbers that make up your data. These ÔassumptionsÕ are actually requirements in the sense that they should be met before the test is used. Parametric tests make more assumptions than do nonparametric tests, but even the latter still make some. You should always check what assumptions are required to be satisfied before you apply the particular test you want to use. The specific requirements of each test will be explained as we describe each test, but many tests, particularly the parametric ones, have a set of common assumptions and we will examine them in general here. The more these requirements are violated, the less confidence you can have in the final p-value. |
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